Telephone-exchange system.



D. M. TAGGAR.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT.25. 1911.

Patented Dec. 80,1919..

I II.

UEETED STATES PATENT GEFIE.

:DAWSON M. TGGART, 0F EAST ORANGE, NEW JERSEY, ASSIGNOR T0 WESTERNELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OE NEWYORK.

TELEPHONE-EXCHANGE SYSTEM.

assente.,

Specification cf Letters Patent.

Patented Dec. 30, 1919.

To all 'whom it may concern:

Be it known that l, DAWSON M. TAGGART, a citizen of the United States,residing at East Grange, in the county of Essex and State of N ewJersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, andexact description.

This invention relates to telephone eX- change systems, and moreparticularly to such systems which employ automatic ringing forsignaling purposes and which are provided with trunk lines extending tochief operators desks, private branch exchanges, information desks andlike positions.

rThe object of this invention is to provide a system of this characterin which the source of ringing current is automatically disconnectedfrom a line before an answering operators telephone set is connectedtherewith, thereby to eliminate the disagreeable clicks which areusually present when an operator answers a call over a line to which isconnected a trunk or cord circuit equipped for automatic ringing.

Another object of this invention is to automatically disconnect thesource of ringing current from an outgoing line immediately uponconnection therewith, to actuate simultaneously a signaling device atthe distant end of the outgoing line, and to connect a source of tonesignaling current to an incoming line which is connected with theoutgoing line, thereby indicating` that the signaling device at thedistant end of the outgoing line has been actuated.

ln accordance with this invention there is provided an outgoing line,such as a trunk circuit extending to an information desk, with whichconnection may be made by an incoming line, such as a cord or trunk circuit equipped for automatic ringing. rlhe trunk circuit is provided withapparatus for causing the actuation of a signaling device at theinformation desk, for disconnecting ringing current from the trunk line,and for connecting a source of tone supply to the incoming line.

For a more complete understanding o1' this invention, reference shouldbe had to the following description considered in connection with theaccompanying drawing, wherein Figure 1 shows a system containing oneembodiment of this invention, and Fig. 2 shows a modied form thereof.

Referring to Fig. 1 there is shown a cord circuit A. located at onesection C of a switchboard, and a trunk circuit B extending from thissection C to section D, at which there is a signaling device, alistening key and an operators telephone set. The cord circuit A isconnected with a telephone line E and serves to extend this line forconnection with the trunk circuit B. It is believed this invention willbe fully underA stood from a description of the operation of the systemshown in the drawing.

he operator at section C, upon receiving a request from connectedcalling station E for connection with the information operator locatedat section l), inserts plug 5 of cord circuit A into j ack 6 of thetrunk circuit B, whereupon lamp 7 is lighted and relay 8 operated over acircuit from battery through the lamp 7 winding of relay 8, sleevecontacts of the plug 5 and jack 6, contact of relay 16, lower normalcontact of relay 17 to ground. rlhe operation of relay S causes theactuation of a ringing relay 9 over a circuit from battery throughresistance 10, winding of relay 9, normal contact of relay 11, contactof tripping relay 12 and the closed contact of relay 8 to ground. rlheoperation of ringing relay 9 connects a source of ringing current 15 tothe trunk circuit B, causing the operation of relay 16 over a circuitfrom the source of ringing current 15 through the winding of trippingrelay 12, the lower alternate contact of ringing relay 9, ring contactsof the plug 5 and jack 6, upper normal contact of relay 17, winding ofrelay 16, tip contacts of the jack G and plug 5, and the upper alternatecontactof ringing relay 9 to ground. The winding of relay 16 is of lowresistance so that as soon as the circuit through this relay iscompleted tripping relay 12 is operated. The tripping relay, inoperating, opens its contact, removing the short circuit from andpermitting the operation of relay 11. Relay 11 is thereupon locked upover a circuit from battery through resistance 10, alternate con-l tactand winding of relay 11, and the contact of relay 8 to ground. Theoperation of relay 11 also establishes a short circuit for ringing relay9, which thereupon releases, removing ringing current from the trunkcircuit.

Upon the establishment of the above mentioned circuit through relay 16,this relay operates, opening its normal contact, thereby removing theshort circuit from relay 1 7, which :immediately operates. Relay 17, inoperating, removes the bridged relay 16 from across the trunk circuit Band closes a Contact in the ring strand of the trunk circuit B. Relay17, in operating, also opens a contact in the short circuit path aboutitself, and in closing its lower alternate contact causes theenergization and operation of the relay 18 over a circuit from batterythrough the winding 'of relay 18, normal contact of relay 19, and thelower alternate contact of relay 17 to ground. Relay 18, in operating,causes the lighting` of lamp 2O which serves as a line signal to thedesk operator. Relay 18, in operating, also opens a Contact in the ringstrand of the trunk circuit B and connects a source of tone supply 21through resistance 22 andcondenserf23 with the incoming line, whichthereby serves as a signal to the calling subscriber E that thesignaling device at the information desk has been actuated. The circuitincluding the source of tone also includes winding 25 of repeating coil26 which is in inductive relation with winding 27 thereof, so thatcurrent from source 21 is induced into the circuit of the callingsubscribers receiver, which includes the winding 27 of the repeatingcoil. In this manner the source lof tone supply is connected with thecalling subscriber. The subscribers line E may be considered asl beingconnected with the trunk circuit B, for the cord circuit A to which thecalling subscribers line is connected, merely serves as an extension ofthe lino E.

The desk operator, upon observing the lighted condition of lamp 20,actuates listening key 30 to connect the telephone set to the trunkcircuit, and causes the operation of relay 19 over a circuit frombattery through the lower contact of listening key 30 and the lowerwinding of relay 19 to ground. Relay 19, in operating, opens the circuitof relay 18 which thereupon releases, extinguishing the lamp 20 anddisconnecting the source of tone supply 21 from the circuit. Relay 19 inoperating also established a locking circuit for itself, which may betraced from battery through the upper winding of relay 19 and alternatecontact thereof, and the lower alternate contact of relay 17 to ground.Relay 19 is now under control of the plug 5 and remains operated untilthe plug 5 is withdrawn from the jack 6, thereby to prevent therelighting. of lamp 20 upon the restoration of listening key 30 tonormal position. Supervisory relay 46 in the cord circuit A is operatedas soon as relay 18 releases to connect a shunt including resistance 10about the lamp 7 to extinguish this lamp. At the conclusion of theconversation, the restoration of listening key 30 to normal positionreleases supervisory relay 16 causing the supervisory lamp 7 to relightto furnish a disconnect signal tothe operator. The operator now removesthe plug 5 from the jack 6, whereupon all apparatus is restored tonormal condition.

1f the trunk circuit and apparatus of Fig. 2 be substituted for thetrunk circuit and apparatus of Fig. 1, and if the plug 5 of cord circuitA is inserted into jack 36, lamp 7 is lighted and relay 8 operated asbefore, and the ringing relay 9 is energized to connect the source ofringing current 15 to the trunk circuit. Upon the operation of ringingrelay 9, a circuit is established from the source of ringing current 15through the winding of tripping relay 12, lower alternate contact ofringing relay 9, ring contacts of plug 5 and jack 36, winding of relay37, condenser 38, tip contacts of the jack 36 and plug 5, and the upperalternate contact of ringing relay 9 to grounc. Relay 37 is thereuponoperated, closing both of its contacts. The closure of its left contactconnects a non-inductive resistance 39 in parallel with the relay 37 andcondenser 38, and thereby establishes a low resistance tripping circuitfor the ringing current whereby relay 12 is operated. Relay 11 is thenactuated and ringing relay 9 releases in the manner hereinbeforedescribed to disconnect the ringing' current from the trunk circuit. Theclosure of the righthand contact of relay 37 causes the operation of thedierential relay l0 over a circuit from battery through the right-handcontact of relay 37 and the left-hand winding of differential relay l()to ground. Relay 40 in operating establishes a locking circuit foritself from battery through the left-hand contact and left-hand windingthereof to ground. The operation of relay 37 also causes lamp 4&1 to belighted, which is then maintained lighted upon the establishnient of thelocking circuit for the differential relay 10, it being understood thatrelay 37 is released immediately upon the release of ringing relay 9.The operation of dierential relay ll0 also connects a source of tonesupply 42 through resistance V43 and condenser la to the cord circuit A,and thence to the calling subscriber E through the inductive action ofthe repeating coil windings.

The operator upon observing the lighted condition of lamp 41 `actuateslistening key l5 to connect the operators telephone set to the trunkcircuit. The actuation of this listening key closes a circuit throughthe righthand winding of differential relay 40, whereby this relayreleases its armatures, eX- tinguishing lamp 41 and disconnecting thesource of tone supply l2 from the .calling subscribers lineV Theactuation of listening key 45 also causes the operation of supervisoryrelay 46 in the cord circuit, which in attracting its armature,establishes a shunt circuit including resistance 10 about the lamp 7,thereby extinguishing the lamp. The extinguishment of this lamp servesas a signal to the operator at switchboard section C that the deskoperator has answered the call. vWhen the desk operator restoreslistening key l5 to normal position, supervisory relay 46 is released,whereupon lamp 7 is lighted to serve as a disconnect signal for theswitchboard operator who may then withdraw the plug 5 from the jack 3G,whereupon the apparatus is restored to normal position.

What is claimed is:

1. In a telephone exchange system, in combination, an incoming and anoutgoing line. means for establishing a connection between said lines,av signaling circuit closed upon the establishment of said connection, arelay in the outgoing line actuated upon the closure of said circuit,means simultaneously operative to render said circuit ineifective, asignaling device, a source of tone supply, and a second relay energizedupon the actuation of the iirst relay to operate the signaling deviceand to connect the source of tone supply with the incoming line.

2. In a telephone exchange system, in combination, an incoming and yanoutgoing line, means for establishing a connection between said lines, asignaling circuit closed upon the establishment of said connection, arelay bridged across the outgoing line actuated upon the closure of saidcircuit, a second relay responsive to the actuation of said bridgedrelay to disconnect the bridged relay rom the outgoing line, a signalingdevice, a source of tone supply, and a third relay actuated upon theresponse of the second .relay to Operate the signaling device and toconnect the source of tone supply with the incoming line.

3. In a telephone exchange system, in combination, an incoming and anoutgoing line, means for establishing a connection between said lines, asignaling circuit closed upon the establishment of said connection, arelay in the outgoing line actuated upon the closure of said circuit,means simultaneously operative to render said circuit ineffective, asignaling device, a source of tone supply, a second relay responsive tothe actuation of the first mentioned relay to cause the operation of thesignaling device and to connect the source of tone supply with theincoming line, an operators telephone set, a switching device forconnecting the operators telephone set with the outgoing line, and meansoperative on the actuation of the switching device to cause thedisconnection of the source or' tone supply from the incoming line.

4. In a telephone exchange system, in combination, an incoming and anoutgoing line, means for establishing a connection between said lines, asignaling circuit closed upon the establishment of said connection, arelay 'bridged `across the outgoing line and actuated upon the closureof said circuit, means simultaneously operative to render said circuitinoperative, a signaling device, a source of tone supply, a second relayenergized upon the actuation of the bridged relay to cause theoper-ation of the signaling device and to connect the source of tonesupply with the incoming line, an operators telephone set, a listeningswitch for connecting the operators telephone set with the outgoingline, and a relay operative upon the actuation of the listening switchto cause the denergization of the second mentioned relay.

5. In a telephone exchange system, in combination, lan incoming and anoutgoing line, means for establishing a connection between said lines, asignaling circuit closed upon the establishment of said connection, arelay bridged across the outgoing line and actuated upon the closure ofsaid circuit, a second relay responsive to the actuation of the bridgedrelay to disconnect the bridged relay from the outgoing line, asignaling device, a source of tone supply, a third relay energized uponthe response of the second relay to Icause the operation of thesignaling device and to connect the source of tone supply with theincoming line, an operators telephone set, `a listening switch forconnecting the telephone set with the outgoing line, a fourth relayenergized upon the actuation of the listening switch to cause thedeenergization of the third relay, and a locking circuit for the fourthrelay established upon the energization thereof.

In witness whereof, I hereunto subscribe my 7name this 19th day ofSeptember, A. D., 191

DAWSON M. TAGGART.

